When Jesus Christ manifests himself to the world he will establish his government over all the earth and there will be peace.
He is doing that presently through His followers.
"For our struggle is not against flesh and blood, but against the rulers, against the powers, against the world forces of this darkness, against the spiritual forces of wickedness in the heavenly places."
His government was established before the cross.
"And Jesus came up and spoke to them, saying, 'All authority has been given to Me in heaven and on earth. Go therefore and make disciples of all the nations, baptizing them in the name of the Father and the Son and the Holy Spirit,…'"
"Rejoice greatly, O daughter of Zion! Shout in triumph, O daughter of Jerusalem! Behold, your king is coming to you; He is just and endowed with salvation, Humble, and mounted on a donkey, Even on a colt, the foal of a donkey."
So the chief priests of the Jews were saying to Pilate, "Do not write, 'The King of the Jews'; but that He said, 'I am King of the Jews.'"
"There will be no end to the increase of His government or of peace, On the throne of David and over his kingdom, To establish it and to uphold it with justice and righteousness From then on and forevermore. The zeal of the LORD of hosts will accomplish this.